Gas discharge tubes and circuit arrangements therefor



Feb. 5, 1957 D. S..RIDLER 3 GAS DISCHARGE TUBES AND CIRCUIT ARRANGEMENTS THEREFOR Original Filed June 10, 1949 .7 s Sheets-Sheet 1 F (9V /G2 T L R3 V I 1 FIRST 1 CATHODE- f"'''' ''fi POTENTIAL vs i /c 26 PULSE V2 V 4 R R4 T" V THIRD CAT/{ODE WN -l I n ve n tor DESMOND 6. Elm E7? Attorney D. S. RIDLER Feb. 5, 1957 GAS DISCHARGE TUBES AND CIRCUIT ARRANGEMENTS THEREFOR Original Filed June 10, 1949 6 Sheets-Sheet 2 kbo Q 2 Q wTm 5T 10 Inventor DESMOND J. AIDLEE By Z Attorney Feb. 5, 1957 D. s. RIDLER 2,780,751

GAS DISCHARGE 'rusrss AND CIRCUIT ARRANGEMENTS THEREFOR Original Filed June 10, 1949 6 Sheets-Sheet 5 I AL I F 6.4. I I

NEGATIVE. COUNT/N6 2 01.555 C/ A l 5 PS Inventor DESMO/VD 5, P/DLER sss SSM sMs SMM MSS MM MMS MMM4 y A ttorne Feb, 5, 1957 D. s. RlDLER 2,780,751

GAS DISCHARGE TUBES AND CIRCUIT ARRANGEMENTS THEREFOR Original Filed June 10, 1949 6 Sheets-Sheet 4 INVENTOR DESMOND 6. RIDLER Feb. 5, "1957 D. s. RIDLER 2,780,751

GAS DISCHARGE TUBES AND CIRCUIT ARRANGEMENTS THEREFOR Original Filed June 10, 1949 e Sheets-Sheet 5 n a INVENTOR DESMO/YD -s. AIDLER Feb. 5, 1957 D. s. RIDLER GAS DISCHARGE TUBES AND CIRCUIT ARRANGEMENTS THEREFOR 6 Sheets-Sheet 6 Original Filed June 10, 1949 Inventor DESMOND S, R/DLER Attorney jnited States GAS DISCHARGE TUBES AND CIRCUIT ARRANGEMENTS THEREFOR This invention relates to gas discharge tubes and circuit arrangements therefor. This application is a continuation of our application Serial No. 100,462, filed June 10, 1949, now abandoned.

The object of the invention is to improve the performance i multi-gap gas tubes, both of the cold cathode or thyratron type.

One feature of the invention comprises a circuit arrangement for a gas filled discharge tube having a plurality of individual anode cathode gaps and circuit connections to and interconnections between a plurality of gaps whereby the firing of one gap causes extinguishment of a second gap already in discharge.

A second feature of the invention comprises a circuit arrangement for a gas-filled discharge tube having a number of individual anode-cathode gaps comprising connections to and interconnections between said gaps whereby a succession of electrical pulses applied to the tube in conjunction with ionisation spread between gaps will cause a single discharge to travel along a succession of gaps, one gap only being under discharge at a time, and whereby the extinguishment of gaps is caused by control of their electrical condition from succeeding gaps in the direction of travel of the discharge.

A third feature comprises a circuit arrangement for a gas filled discharge tube comprising a train of anodecathode gaps and circuit connections to and interconnections between gaps whereby some of the gaps act as transfer gaps for causing a succession of the other gaps to discharge in turn.

The invention will be described with reference to embodiments thereof shown in the accompanying drawings in which:

Fig. 1 shows a circuit arrangement for a gas tube wherein an intermediate gap is used for passing a discharge between two outer gaps in such a way that only one outer gap is discharging at a time.

Fig. 2 shows graphically how the tube shown in Fig. 1 works in response to pulse on the intermediate cathode.

Fig. 3 shows a multi-gap tube working on the principle described in relation to Figs. 1 and 2.

Fig. 4 shows circuit arrangements alternative to those shown in Fig. 3. 4

Fig. 5 shows diagrammatically a known arrangement of gas tubes for responding to binary code impulses, such as a teleprinter impulses.

Figs. 6A and 6B which should be considered together show a binary code impulse receiver incorporating a multig'ap tube working on the principle described in relation to Figs. 1 and 2 which replaces the tube arrangement referred to in connection with Fig. 5.

Fig. 7 shows a possible arrangement of electrodes for a code receiver multi-gap tube.

Fig. 8 is a diagrammatic arrangement of a multi-gap tube somewhat similar to that included in Fig. 6A but which is modified to be included'in a binary code impulse transmitting circuit such as a teleprinter sender.

Fig. 1 shows a gas tube with three cathodes 1C, 20,

3C and a common anode A. The anode A is connected by a resistance R3 to'positive potential V e. g. 220 volts. The firstand third cathodes 1C, 3C are each independently connected to a resistance capacity network C1, R, C2, R2, connected. to earth. The intermediate cathode ZCis connected via'a resistance R4 to the cursor of a potentiometer R5 connected between positive potential and earth. The lead between R4 and the cursor of the potentiometer is connected via a condenser C3 to a pulse source PS.

Assume that current is initially flowing through R3, between the common anode A and the cathode 1C, and via resistance R1 to earth, condenser C1 being charged. The battery potential is divided between resistance R3, the gap between A and 1 C and resistance R. Let us call these three potentials V1 across R3, VS across the gap, and V2 across R1. V1 and V2 may for example each be 60 volts, and VS, the tube sustaining voltage, volts. i

Let us call the potentials on cathode 2C, VB. This will be adjusted by means of the potentiometer R5 to equal V2. The potentialof the third cathode 3C is zero. This condition is shown at the left hand side of Fig. 2 in which the three curves show the potential on the first cathode, the second cathode and the third cathode respectively.

A negative pulse of potential 'V2 is applied via the condenser C3 to resistance R4 with the results indicated at the first vertical broken line in Fig. 2. The potential on the centre cathode 2C is reduced to zero, and owing to ionisation coupling, as described in U. S. application No. 763,655, filed July 25, 1947, now Patent No. 2,663,68 l,'the' discharge transfers to thatgap, because the potential across the gap is increased from VS to VS+ V2'.

The Whole of the potential is now divided between the second gap and resistance R3. As the second gap sustains at potential VS, the potential across R3 now rises to Vl-l-VZ and this in turn causes the potential across the first gap to be reduced from VS to VS'V2. The potential of the first gap is therefore reduced below the sustaining potential a'nd the first gap is extinguished. can; denser Cll now discharges and the potential on the first cathode rapidly decreases to zero; At the end of the pulse, the potential on cathode 2C returns to value VB=V2, so that the potential across R3 returns to V1. This condition is shown at the second vertical broken line'in Fig. 2. The potential across the third gap now becomes VS+ V2 and ionisation coupling causes this gap to fire. The potential across the second gap is now reduced to VS V2 while the cathode 3C is at earth'potential and condenser C2 is charging and in consequence the centre gap is extinguished in the same way that the'first gap was extinguished. These operations areindicated in Fig; 2 between the second and third broken'vertical lines. The potential on the first cathode 1C falls to zero due to discharge of condenser C1 with time constant Ci, R1, and the third cathode 3C rises to a potential V2 with time constant It will be seen that an electrical impulse applied to the second gap 2C while the first gap 1C is under discharge automatically causes the transfer of the discharge from the first gap 1C to the third gap 3C, the first gap iC being extinguished.

The second gap may or may not temporarily discharge in the process. i

It will also be appreciated that an electrical impulse received at the cathode of the second gap 2C in conjunction with ionisation spread from a gap 1C will causegap 13C to discharge. A change in ihfi electrical condition of gap 1C due to the discharge of 2C causes gap 10 to extinguish. This extinction is therefore related to a change in condition of gap 3C for its striking is also due to the discharge of 2C.

If now a second pulse is applied to cathode 20, the discharge is transferred back to the first gap in a similar way, as indicated by the potential changes indicated between the third and fourth broken vertical lines in Fig. 2.

For satisfactory operation of this arrangement, it is necessary that ionisation coupling between the first and the third gaps should be less than between the first and the second gaps. In one practical case current in the first gap reduced the break-down potential of the second gap to within about 40 volts of sustaining potential and the breakdown potential of the third gap to within 80 volts of sustaining potential. A counter with V2 equal to say 60 volts should thus function with a reasonable margin of safety, and experiment has shown this to be the case. An electrode having the function of transferring the glow from one cathode to another, as in the case of 2C, is hereinafter referred to as a transfer electrode.

Fig. 3 shows an extension of the use of the transfer electrode in a distributor tube having a large number of cathodes.

Transfer electrodes 26, 4C, 6C are spaced between the working cathodes 1C, 3C, 5C Sets of alternate transfer electrodes 20, 6C and 4C, 8C are respectively commoned and connected via separate impulsing circuits R41, R43, C31, and R42, R44, C32 to a common bias supply. Any well-known means may be provided for applying negative voltage pulses to C31 and C32. If the gap anode A/ cathode C1 is initially conducting, the first pulse applied to input 1 transfers the glow via the first transfer electrode 2C to the second working gap A/3C. The second pulse arrives on input 2 and further transfers the glow to gap 5C and so on. A potential of, say, 60 volts appears across each RC cathode lead when the appropriate working gap conducts.

A useful feature inherent in this type of counter is that the direction in which the glow moves is determined by the position of the next or first pulse vis-a-vis the conducting gap, e. g. if the first pulse arrives on input 1 when A/3C is conducting the glow moves from right to left and if the first pulse arrives on input 2 it moves from left to right. This feature is suited to digital control such as is used in automatic telephone systems and may be used as a dial impulse regenerator since the digit may be counted in, and, when required, counted out in reverse. This avoids the difficulties of working with complementary numbers.

When individual cathode outputs are not required, alternate cathodes may be commoned and the number of RC networks reduced to two. Fig. 4 shows this simplification. Means are also shown for switching the incoming counting pulses by means of the potential across the cathode loads. If a reversal in the direction of the glow is required the connections between the rectifiers MR1, MR2,

and the cathodes are reversed. Working electrodes 1,

5, 9 and 3,7, 11 are separately multiplied and each multiple is connected to a resistance capacity network, C4, R4, and C3, R3 respectively.

Transfer electrodes 2, 6, and 4, 8, 12 are also separately multipled and each multiple is connected via a resistance R5, R6, respectively, to a positive bias potential 80V as against the anode potential of 220 volts.

The common anode A is connected to battery via resistance R7 which drops the 220 volts battery potential to 160 volts. Each transfer multiple is connected via a condenser C2, C1, and resistance R2, R1 via a common resistance R8 to 60 volts positive, and via a condenser CS to a source PS of negative pulses of 60 volts potential.

The pulse connects are each connected from between the condenser and resistance via a reversed rectifier MR2,

MR1, and a two-way two-contact switch S1, S2, to the working cathode multiples.

It will be seen that a pulse via PS is connected to both transfer multiples but be ncutralised on one of said multiples in the following way:

The working gap which is under discharge will have a 60 volt positive potential present on its multiple and this will be effective via S1 or S2 and the corresponding rectifier MR1 or MR2 on the transfer gap multiple so connected, so that although the negative pulse reduces the potential on the pulse side of the resistance R1 or R2 to zero, positive potential still exists on the electrode side of R1 or R2 and in consequence firing potential is not applied via the said transfer multiple.

According to which way the switch S1, S2, is set, the discharge will move upwards or downwards as shown. It gap 3 is discharging potential thereon is connected back via S1, MR1 to neutralise pulses via C1 to cathode 4, so that a pulse will act via R2, C2 only, to cause gap 2 to fire, and the discharge will move downwards. If, however, switch S1, S2 were in the reverse position, potential from cathode 3, would be connected via S2, MR2 to neutralise pulses via C2 to cathode 2, so that a pulse will act via R1, C1 only to cause gap 4 to fire, and the discharge will move upwards.

It will be seen that although the working cathodes are connected in groups to common networks, no ditficulty will arise since only one group at a time has a cathode potential connected thereto. Similarly, the commoning of the pulse connections to the transfer electrodes is without undesirable result since only the transfer gaps adjacent a gap under discharge can fire by ionisation coupling and one or other of these gaps is isolated from the pulse lead by the cathode potential connected to corresponding transfer cathode multiple.

The counter shown in Fig. 4 is intended for use as a dial impulse storage element. Impulses representing a digit cause the movement of the discharge from the initial position to a cathode related to the stored number. When this is later required, the switch S is operated and the glow is impulsed in the opposite direction. The number of impulses required to return the discharge to the normal position represents the stored number.

Assume that the first gap 1 has been initially rendered conducting by application of a transient potential to a trigger electrode T. Current flows through resistor R7 gap 1, resistor R4 to earth. If a negative counting pulse is now applied to condenser C5, it is effectively switched through C2 since MR1 appears as a low resistance compared with R1 and the potential across R4 makes MR2 appear high compared with R2. The negative pulse therefore transfers the discharge from gap 1 to gap 3 through gap 2 as previously described. Now, the potential originally supplied to MR2 changes to MR1 and the second counting pulse is switched through condenser C1. In this way the effect of two trains of out-of-phase counting pulses is obtained by using the potential which occurs alternately across resistance R3 and R4.

If three impulses are applied, the discharge reaches gap 7. If the switch S is operated, the positive potential is changed from MR1 to MR2 and a first reverse counting pulse is transmitted through C2 to transfer the flow back to gap 5. Likewise, second and third impulses move the discharge to gap 3 and gap 1 respectively.

The trigger electrode T may be used to give an electrical indication that the glow is at the origin since it will act as a probe in the first gap and derive a potential from the discharge.

There is a requirement in telegraphy for a counter which can select a particular outlet in response to a teleprinter signal. This has already been achieved with a number of individual tubes arranged in a pyramid as shown in Fig. 5, and as described in U. S. application No. 744,010/47.

Such an outlet is connected so. that when that outlet-ischosen: a" printing mechanism can be. operated to print;

the appropriate character. The telegraph code signals received are usually of the two condition type, that is a binary code, and, the two types ofsi'gnals'are conveniently termed marlCand space. One may well be. a suitable voltage applied to the line and the other a zero condition but the particular composition of the mark and. space signals does not affect the present issue.

For convenience of description it will be assumed that each character which it is desired to receive and record is composed of a permutation of three successive. elements one character for example being mark, mark, space or briefly MMS. It is common. practice to precede the character elements by a start signal, generally a space element and to follow them by a stop signal, ordinarily a mark element. A complete signal combination therefore might well be SMMSM.

Returning to the question of receiving a binary code impulse signal of the kind described and automatically selecting in response to such reception a unique outlet it may be mentioned that one method of achieving this result has already been described in our U. S. application No. 744,010/47. Apart from other equipment with which we are at present not concerned the main feature of the telegraph receiver there described is provided by a number of individual gas discharge tubes arranged in pyramid form as indicated diagrammatically in Fig. 5. In that figure the tubes are represented by the larger filled.- in circles whilst the smaller open circles are points to which pulses representative of space and mark received elements are fed, the space pulses in common to those circles marked S and the mark to those marked M. The lines joining various tubes represent circuit connections by means of which certain tubes on operation prime two other tubes. For one of those other tubes to be fired the intervening S or M pulse reception point must first receive a pulse. The initial condition of the tubes is with the apex tube struck and therefore priming the other two tubes to which it is connected. If the character received is represented by the elements MMS, pulses representative of these will be applied in turn to the appropriate pulse reception points and the route through the tube pyramid wiil lead finally to the tube next to the right hand end of the pyramid base being brought into a discharging condition. Against each of the pyramid base tubes it will be noticed that there is marked the unique mark and space combination required to operate that tube.

The present invention provides a more economical method of achieving a unique outlet for each coded character received at a telegraph receiver. A single tube invcorporating within its envelope a similar arrangement to that described above in relation to Fig. 5, is included in the telegraph binary code impulse receiver shown in some detail in Figs. 6A and 6B.

Referring first to Fig. 6A there will be seen a multigap tube TMG having a single anode AN, a number of cathodes, all shown as filled-in circles like CA, and transfer electrodes, all shown as open circles like TE. The transfer electrodes are commoned up as were the pulse reception points of Fig. and fulfil a similar function. A

discharge between the anode AN and the apex cathode is transferred to the gap between the anode and one of the right base cathodes according to the mark and space elements received. In this way a peculiar condition is achieved at one outlet of thetube whenever a signal combination is received. This peculiar condition is arranged to operate a relay which in turn controls printing mechanism of known kind.

Considering the complete receiver circuit of Figs. 6A and 6B and inparticular the tubes T1 to T5.

When the tube T1 is conducting, current flowsthrough resistances 11 and 12 between cathodes 10 and earth. The resistances 11 and 12 arfimwportioned 'tO giYg a suitle o t r p be we n ca ode. nd ar h a tl hsl junction point of these resistances is connected (over, a. resistance 14) to the control electrode of tube, T2,

In the initial condition of the circuit of Figs. 6A and v 6B tube T1 is conducting and a potential difference, is impressed from its cathode circuit between the control electrode and cathode of tube T2. This potential difference is about 35. volts, which is insufficient to cause the tube to become conducting, the potential difference required for this purpose being about 70 volts. 4

The incoming line 15 Fig. 6B is connected over windings, of telegraph relays 16 and 17 to ground. As in the normal, non-signalling condition of line 15 marking potential is impressed thereon at the transmitting station, the contacts 18 and 19 of these relays are, in marking position. The cathode of tube T1 Fig. 6A is connected over a conductor 20 to the marking contact of contacts 19 and thus through a condenser 21 and ground. Con: denser 21 is thus kept charged.

Fig. 6B shows the circuits of an impulse generator and the means by which it is started into operation. impulse generator comprises two pentodes 22 and 23 connected in well known manner as a multivibrator. The anode potentials are supplied from a source stabilised by means of a neon-tube stabiliser 24. The normal grid potentials are adjusted by means of potentiometers 25 and 26, the sliding contact on 25 serving to adjust the frequency and that on 26 the relative times of operation of the two tubes. The impulses are derived from the grids of pentodes 22 and 23, these grids being connected over respective condensers to the grids of triodes 27, 28 so that the changes of potential on the grids of pentodes 22 and 23 being thus differentiated to produce positive impulses on conductors 28 and 29 connected to the anodes of those triodes.

The multivibrator is held in non-operating condition by the cathode of tube 22 being normally connected to positive potential. A three electrode cold cathode tube 31 is normally conducting and current therefore flows through resistance 32 connected to the cathode thereof, the positive end of this resistance being connected to the cathode of pentode 22. There is a second three electrode cold cathode tube 33, which is normally non-conducting, the anode of which is connected over a condenser 34 to the anode of tube 30.

The spacing contact of contacts 21 is connected to earth over the primary of a step-up transformer 35, the secondary of which is connected to the control electrode of tube 33. When therefore the start element of a teleprinter code combination is received and contacts 18 and U of relays 16 and 17 change over to spacingposition, condenser 21 is discharged through the primary of trans} former 35. The resultant potential acrossthe secondary of this transformer 35 is impressed between control electrode and cathode of tube 33 and is sufficient to ionise the gap between those electrodes and the tube 33 be comes conducting. The interconnection of the anodesof tubes 31 and 33 through condenser 34 results in tube 31 becoming non-conducting and the disappearance of the positive bias on the cathode of pentode 22.

The positive bias on the cathode of pentode 22 has held this pentode from passing current and the mainvibrator is therefore normally in the position in which anode current in pentode 23 is a maximum. Whenlthe positive potential on the cathode of tube 22 is removed the grid of that tube becomes positive with respect to the cathode and the tube 22 passes current 'a id the anode current rapidly rises to a maximum and remains so until the condenser connecting the anodeof 'pentode 22 to the grid of pentode 23 has dischargedj vPentode 23 then passes current and there is asudderi drop i'n the potential of the grid of pentode 22. This .suddenidrop in potential is differentiated by condenser 36 am a posi- .tive pulse is created on conductor 29coiai' ccted'tothe sands s ub Thg-ptrbs s ennlt g a q pay be set so that this pulse occurs milliseconds after the commencement of its operation and thus at the midpoint of the period of milliseconds for the start element of the incoming signal (for a teleprinter signalling speed of 50 bands).

Conductor 29 is connected to a condenser 27 which in turn is connected over an individual condenser resistance combination to the control electrodes of tubes T2 T5. The value of the potential thus impressed on these control electrodes is insuflicient to ionise the gap between control electrode and cathode of any of the tubes, but added to the potential impressed on the control electrode of tube T2 from the cathode circuit of tube T1 is sufficient to cause tube 2 to become conducting.

When tube 2 becomes conducting a potential is impressed from its cathode circuit upon the control electrode of tube T3 (and also upon the first transfer electrodes of tube TMG) and upon the next occurrence of an impulse on conductor 37, i. e. after a period of 20 milliseconds, tube T3 becomes conducting. This in turn impresses a potential upon tube T4. in this way tubes T3, 4 and 5 become conducting on the occurrence of successive impulses.

It should be noted that the anodes of all the tubes T1 T5 are connected to positive potential over a common resistance 38, which is of such value that when a tube such as tube T2 becomes conducting the potential upon the anode of any other tube, such as T1, that is at that moment conducting is depressed below the value necessary to keep the tube conducting when only a very low potential is applied across the gap between control electrode and cathode. The consequence is that when any tube in the chain T1 T5 becomes conducting the preceding tube in the chain becomes non-conducting.

To consolidate the understanding of the functions of tubes T1 to T5 it may be said that tube T1 is a pilot tube, normally conducting and corresponding to the stop element of the code. Tube T2 corresponds to the start element of the code and tubes T3 T 5 to the code elements. The tubes T2 T5, operated sequentially by the impulses on conductor 37, time the intervals occupied by the elements of the code, becoming conducting at the mid-points of the elements allotted to the code.

The cathode circuit of tube T5 is connected over conductor 39 to the control electrode of a cold cathode tube 40 (Fig. 6B) which control electrode is also connected to conductor 30. The impulse generator applies an impulse to conductor ten milliseconds after each impulse applied to conductors 29 and 37 so that when tube T5 has been conducting for ten milliseconds tube becomes conducting. The cathode of this tube 40 is connected to ground over the primary of a step up transformer 41, the secondary of which is connected to the control electrode of tube 31. The potential thus impressed, when tube 40 becomes conducting, upon the control gap of tube 31 causes that tube to become conducting. Owing to the connection between the anodes of tubes 31 and 33 over condenser 34, tube 33 becomes non-conducting. Another effect of tube 31 becoming conducting is to impress a positive potential upon the cathode of pentode 22 and so stop the impulse generator. Tube 40 is connected so as to be self extinguishing.

The secondary of transformer 41 is connected over a conductor 42 to the control electrode of tube T1 and the impulse delivered when tube 40 becomes conducting also causes tube T1 to become conducting. Tube T5 is thereby rendered non-conducting.

So far no reference has been made to the effect of the receipt of the code elements of a signal. The operation for receipt of the complete signal SMMSM is as follows:

Tube T2 is made conducting when the start element of a teleprinter signal is received, as described above, and a potential is thereby passed not only to the control electrode of tube T3 but also to the first transfer electrodes of tube TMG over lead 64. The second impulse on conductor 29 occurs at an interval of 20 milliseconds after the first impulse, i. e. in the middle of the interval allotted to the first code element of the received signal. Conductor 29 is connected to the moving tongue of contacts 18 and if at this moment a marking impulse is being received, so that contacts 18 are in marking position, this impulse is applied over conductor '51 to certain transfer electrodes of tube TMG.

It will be noted that leads and 51 both have flipdlop circuits FFl and FF2 included in them. These are arranged so that alternate pulses on a. lead, say 50 are directed to the leads and 61 in turn and on 51 to 62 and 65 in turn. The mark lead 50 is connected over 60 and 61 with two sets of transfer electrodes, namely the electrode 65 and the electrodes 66 and 67. Over connection 68 pulses are received at the commencement of each character combination from tube T2. These ensure that the first element produces always either a pulse over lead 60 or lead 62.

The initial element representative of the transmitted character is a mark so that a potential is applied over leads 50 and 60. When the tube T2 is fired a negative pulse is produced over lead 64 and because of the inverting effect of transformer XR a positive pulse is passed to the apex cathode and a discharge is caused between that cathode and anode AN and any previous discharge extinguished. A pulse now appearing at transfer electrode 65 as a result of the receipt of a mark element is operable to transfer the discharge to cathode CA2. Following mark and space character elements, namely MS in the example considered effect the transfer of the discharge finally to the gap anode AN/cathode CA3. Each base cathode such as CA3 is connected to an individual outlet circuit such as the rectifier-resistance parallel network 69, condenser 70, triode amplifier 71 and relay 72. The present received character results in a relay 73 being operated. This controls a printing operation corresponding to the character-received.

An additional cold-cathode tube 79 is provided having its anode connected to the anode of tube TMG. The control electrode of tube 79 is connected to the conductor 42, so that when, at the end of the period allotted to the receipt of a start-stop teleprinter code tube T1 is made conducting by an impulse from the secondary of transformer 41 over conductor 42, as above described, tube 59 is also made conducting. The common anode connection ensures that the tube TMG is then made non-conducting. Thus TMG is ready for the receipt of a further code combination. Tube 79 will be rendered non-conducting during the receipt of a subsequent code combination as soon as the tube TMG becomes conducting.

A permutation code of three units has been assumed for purposes of illustration, but the scheme may be applied to the standard five unit code in which case it is necessary to select one of the thirty-two outlets.

Fig. 7 shows a more correct arrangement and spacing of the electrode array of the tube TMG shown in Fig. 6A. This ensures correct operation, the discharge moving to the right or to the left of the starting point cathode according as the first pulse is a Mark or a Space.

Referring now to Fig. 8 we have the basic multigap tube circuit for a binary impulse code transmitter. The tube is of the same general construction as TMG which is shown in Fig. 6, but has two additional stages of transfer plus main gaps, each equal in number to the last stage of the pyramid. The transfer cathodes are indicated by the etters X, Y, respectively indicating that out-of-phase trains of voltage pulses are applied to the X and Y transfer cathodes respectively. The connections to the transfer cathodes are not shown, but will be similar to those shown in Fig. 3, each stage of transfer cathodes in Fig. 8 being treated as one of the transfer cathodes in Fig. 43. The main cathodes are indicated by circles enclosing an M or an S according as the cathode is required to generate a mark or space signal. The anode is indicated diagrammatically at AN. It will be seen that all the main cathodes are connected to one or other of four leads each connected via :a resistance capacity coupling R1, C1 R, C4, to the mark and space winding of a telegraph sending relay SR whose signalling contacts are indicated at srl.

The final stages of main cathodes are called base cathodes and are all connected via R3, C3, to the mark winding of relay SR to set up the rest position over a signal channel. Each of the last stage gaps may be fired individually by any well known means in response to the operation of a key representing the character which it is desired to transmit. The mark winding of relay Sr is thereby energised and contact srl is held on its M contact. When the pulse trains are applied to the transfer cathodes X, Y, the first pulse on the X cathodes will cause the discharge on say, cathode 6, to be transferred to the corresponding gap in the start unit stage. Extinguishment of gap 6 in the base cathode stage de-energises winding M and discharge of the gap in the start unit stage energises winding S and contact srl changes over to contact S to send a space signal.

The next Y pulse transfers the discharge to the corresponding gap in the last stage of the pyramid. In each stage of the pyramid, some gaps are required to generate marks and other spaces. Mark cathodes in alternate stages are multipled together and space cathodes are also multipled together, there being two sets of multiples for each type of signal, the multiples being individually connected via the resistance-capacity couplings RlCl R403 to the respective windings of relay SR.

The sequence of gaps which will fire in turn is predetermined by the selection of the initial gap since each gap in each stage can only influence a single gap in the next stage in the present direction of working. The sequence of gaps which for if gap 6 in the base cathode stage is initially fired is indicated by a broken line and the code SMSM--M will be sent, the stop unit M being always sent under control of the apex or first stage gap. Every combination of the three unit binary code can be sent by the tube shown.

While the principles of the invention have been described above in connection with specific embodiments, and particular modifications thereof, it is to be clearly understood that this description is made only by way of example and not as a limitation on the scope of the invention.

What I claim is:

l. A gas tube circuit comprising a gas tube having anode electrode means and cathode electrode means, one of said means being divided into a plurality of elements, each element forming with the other of said electrode means a discharge gap with successive gaps being arranged adjacent each other to provide ionisation coupling therebetween, a first and second of said gaps, serving as Working gaps, being separated by a single transfer gap, each of said gaps requiring a given striking voltage to initiate a discharge in the presence of ionisation thereat, and a given maintaining potential to maintain the discharge, a source of potential coupled to said working gaps of a voltage at least equal to said striking voltage, a common resistor in series with all of said gaps, means for applying a striking voltage pulse to said transfer gap of sufficient value to fire it in the presence of ionisation thereat produced by the discharge of said first working gap, said common resistor having a value such that the firing of said transfer gap so increases the potential drop across said common resistor as to lower the potential across the first Working gap below the maintaining potential and to extinguish it, the potential drop across Said common resistor falling after the termination of said pulse to raise the potential across the working gaps to the striking voltage, the second working gap firing due to the ionisation coupling between it and the transfer gap, the discharge of said transfer gap extinguishing after the termination of said pulse, and means for maintaining the potential across the first working gap below the striking voltage until sufiicient deionisation has occurred at said first working gap to prevent firing thereof upon restoration of the potential at said first working gap to said striking voltage.

2. A gas tube circuit comprising a gas tube having anode electrode means and cathode electrode means, one of said means being divided into a plurality of elements, each element forming with the other of said electrode means a discharge gap with successive gaps being arranged adjacent each other to provide ionisation coupling therebetween, a first and second of said gaps, serving as working gaps, being separated by a single transfer gap, eachv of said gaps requiring a given striking voltage to initiate a discharge in the presence of ionisation thereat, and a given maintaining potential to maintain the dis charge, a source of potential coupled to said gaps of a voltage at least equal to said striking voltage, means for normally biasing said transfer gaps to maintaining potential, below said striking potential, a common resistor in series with all of said gaps, means for applying a striking voltage pulse to said transfer gap of suiricient value to fire it in the presence of ionisation thereat produced by the discharge of said first working gap, said common resistor having a value such that the firing of said transfer gap so increases the potential drop across said common resistor as to lower the potential across the first working gap below the maintaining potential and to extinguish it, the potential drop across said common resistor falling after the termination of said pulse to raise the potential across the working gaps to the striking voltage, the second working gap firing due to the ionisation coupling between it and the transfer gap, thereby again increasing the voltage drop across the common resistor and lowering the potential of the transfer gap to extinguish it, and means for maintaining the potential across the first working gap below the striking voltage until sufficient deionisation has occurred at said first working gap to prevent firing thereof upon restoration of the potential at said first working gap to said striking voltage.

3. A gas tube circuit according to claim 2 wherein said means for maintaining the potential across the first work gap below the striking voltage comprises a resistancecapacitance circuit in series with said first working gap.

4. A gas tube circuit according to claim 2 wherein said elements are cathodes and said other electrode is a common anode, and said common resistor, is in series with said anode.

5. A gas tube counting circuit comprising a gas tube having anode electrode means and cathode electrode means, one of said means being divided into a plurality of elements, each element forming with the other of said electrode means a discharge gap with successive gaps being arranged adjacent each other to provide ionisation coupling therebetween, alternate gaps serving as working gaps and being separated by transfer gaps, each of said gaps requiring a given striking voltage to initiate a discharge in the presence of ionisation thereat, and a given maintaining potential to maintain the discharge, a source of potential coupled to said gaps of a voltage at least equal to said striking voltage, means for normally biasing said transfer gaps to maintaining potential, below said striking potential, a common resistor in series with all of said gaps, means for applying a striking voltage pulse to alternate transfer gaps of sulficient value to fire them in the presence of ionisation thereat produced by the discharge of an adjacent Working gap, said common resistor having a "alue such that the firing of a transfer gap so increases the potential drop across said common resistor as to lower the potential across said adjacent working gap below the maintaining potential and to extinguish it, the potential drop across said common resistor falling after the termination of said pulse to raise the potential across the working gaps to the striking voltage, the other working gap adjacent the fired transfer gap firing due to the ionisation coupling between it and said fired transfer gap, thereby again increasing the voltage drop across the common resistor and owering the pot n a Qfthefi d n fe san oext nauish it, means for maintaining the potential across said adjacent working. gap below the striking voltage until sufficient deionisation has occurred at said adjacent working gap to prevent firing thereof upon restoration of the potential at said adjacent working gap to said striking voltage, and means for applying a striking voltage pulse to the transfer gaps between saidalternate transfer gaps to reverse the direction of transfer of the discharge between the working gaps.

6. A gas tube counting circuit according to claim 5 wherein said means for maintaining the potential across said adjacent working gap below the strikingvoltage comprises a time, constant circuit in series with each of said working gaps.

7. A gas tube counting circuit according to claim 5 wherein connections are provided coupling alternate working gaps together to provide two sets of working gaps and wherein said means for maintaining the potential across said adjacent working gap below the striking voltage comprises a separate time constant circuit in series with each of said sets of working gaps.

8. A gas tube circuit comprising a gas tube having anode electrode means and cathode electrode means forming a plurality of successive gaps with adjacent gaps having ionisation coupling therebetween, a first and second working gap, with only a single transfer gap therebetwcen, a source of potential coupled to all of said gaps of a voltage at least equal to their striking voltage,"a common resistor in series with all of said gaps of a value such that only one gap can fire at a time, means for applying a pulse to said transfer gap to fire said gap in the presence of ionisation thereat from the first working gap and spread the ionisation to the second working gap, and means for maintaining the potential across the first working gap below the striking voltage until sutficient deionisation has occurred at said first working gap to prevent firing thereof upon restoration of the potential at said first working gap to said striking voltage.

9. A glow discharge device comprising a plurality of cathode arranged in a branching array, said cathodes comprising a starter cathode at the initial point of said array, a plurality of stages of rest cathodes in order in said array each having twice the number of cathodes of the preceding stage, said plurality of stages including a first stage of two rest cathodes, alternative transfer cathodes between said starter cathode and said first stage of two rest cathodes, and alternative transfer cathodes between each rest cathode and two rest cathodes of the succeeding stage, and an anode adjacent all of said cathodes.

10. A glow discharge device in accordance with claim 9 wherein one group of said alternative transfer cathodes are electrically connected together and the other group of said alternative transfer cathodes are electrically connected together.

11. Translating means comprising a glow discharge device having a plurality of cathodes arranged in abranching array, said cathodes comprising a starter cathode at the initial point of said array, a plurality of stages of rest cathodes in order in said array including a first stage of two rest cathodes, each stage having twice the number of cathodes of the preceding stage, alternative transfer cathodes between said starter cathode and said first stage of two rest cathodes, and alternative transfer cathodes be-. tween each rest cathode and two rest cathodes of the succeeding stage, said alternative transfer cathodes being.

half the number of cathodes of the preceding stage, means for initiating a discharge between anyone cathode of the first stage and said anode in response to a signal corresponding to a decimal number, means connecting alternate cathodes of each stage together, and means for stepping a. discharge initiated between said one cathode of said first stage and said anode along a unique path of cathodes in said array to generate in time sequence output signals on said connecting means corresponding to the binary equivalent of the decimal code of the signal that initiated the discharge at the cathode of said first StLtgC.

13. A circuit for a cold cathode discharge tube comprising an array of inter-electrode discharge gaps, said array comprising a plurality of main gaps and at least one transfer gap intermediate a pair of main gaps, means for firing one of said main gaps, means in said tube for reducing the striking potential across an unfired gap adiacent a fired gap, means for applying an input pulse to said transfer gap, said pulse in conjunction with said striking potential reducing means adapted to cause said transfer gap to fire, and common means connected to said array of gaps for extinguishing said fired main gap upon firing of said transfer gap.

14. A. circuit for a cold cathode discharge tube as claimed in claim 13, further comprising means for firing said other unfired main gap upon cessation of said pulse and extinguishment of said transfer gap.

15. A circuit for a cold cathode discharge tube as claimed in claim 13, wherein one of the electrodes in said array is common to each of said gaps.

16. A circuit for a cold cathode discharge tube as claimed in claim 15, wherein said means for firing said other unfired main gap comprises a plurality of resistancecapacity paraliel network connected respectively in series wit]. the individual electrodes which comprise said main gaps.

17. A circuit for a cold cathode discharge tube as claimed in claim 13, wherein said common extinguishing means comprises an impedance serially connected to an electrode of said array.

18. A circuit for a cold cathode discharge tube as claimed in claim 13, wherein said means for reducing striking potential comprises an ionisable gas.

19. A circuit for a cold cathode discharge tube comprising an array of inter-electrode discharge gaps, said array comprising a plurality of main gaps, and a plurality of transfer gaps, a transfer gap interposed between successive pairs of said main gaps, means for firing one of said main gaps, means in said tube for reducing the striking potential across an unfired gap adjacent a fired gap, means for applying input pulses in common to said interposed transfer gaps, said pulse in conjunction with said striking potential reducing means adapted to cause said transfer gap to fire, andcommon means connected to said array of gaps for extinguishing said fired main gap upon firing of said transfer gap.

20. A circuit for a cold cathode discharge tube as claimed in claim 19, further comprising means for firing a next succeeding main gap in said array upon cessation of an'input pulse and extinguishment of a transfer gap which'fired responsive to the application of said pulse.

21. A circuit for a cold cathode discharge tube as claimed in claim 19, wherein one of the electrodes in. said array is common to all of said gaps.

22. A circuit for a cold cathode discharge tube as claimed in claim 20, wherein said means for firingsuo 'cessive main gaps in-said array comprises a separate re sistance capacity parallel network serially connected to each of said main gapgroups.

23; A circuit for a cold cathode discharge tube as claimed in claim 19, wherein said main gaps are divided into a plurality of groups and said transfer gaps are divided into a. plurality of groups, the individual gaps of said groups being arranged so that a main gap from each 13 of said main gap groups is alternately disposed with respect to each other along the array with a transfer gap from each of said transfer gap groups alternately disposed with respect to each other along the array interposed between adjacent of said main gaps.

24. A circuit for a cold cathode discharge tube as claimed in claim 23, wherein said means for applying input pulses to said transfer gaps comprises means for applying separate pulses to each of said transfer gap groups.

25. A gas tube circuit according to claim 2 further including a separate resistor in series with each of said gaps and a capacitor in shunt across the resistors of the working gaps.

References Cited in the file of this patent UNITED STATES PATENTS 1,898,626 Healy Feb. 21, 1933 14 Hadekel Oct. 31, 1944 Overbcck Sept. 16, 1947 Wales June 15, 194.8 Lyman June 14, 1949 McWhirter Feb. 28, 1950 Reeves Apr. 25, 1950 Loughren May 15, 1951 Townsend Aug. 5, 1952 Depp Nov. 3. 1953 

